Use of starch/xanthan gum combinations as thickeners of cocoa syrups

The influence of starch-xanthan thickening systems on the sensory, textural and rheological properties of cocoa syrups was studied. The results of whole and partial sensory analyses of syrups obtained under laboratory conditions were presented and compared to those of commercially available syrups. In the evaluation of texture such parameters as hardness, adhesiveness, cohesiveness, gumminess and stringiness were considered. The results of rheological measurements were presented in the form of flow curves as well as viscosity/time and viscosity/ temperature relationships. Flow curves were fitted to the models of Ostwald-de Waele and Casson, which allowed characterising the syrups under study to non-Newtonian, pseudoplastic, and thixotropic fluids. It was concluded that the quantity of thickeners used influenced not only theological, but also textural and sensory properties of the syrups. The decrease of pseudoplasticity and hardness with an increase of xanthan addition was a result of high sugars level in the syrups. This phenomenon was a result of competition between sugars (mono-, di-, and oligosaccharides) and hydrocolloids for water molecules in the systems under study.